URL: https://bugzilla.kernel.org/show_bug.cgi?id=153641
Lukas Lueg 2016-08-23 19:54:45 UTC

Created attachment 229941 [details]
Image triggering btrfsck into asan error

The filesystem-image attached to this bug drives btrfsck from btrfs-progs
v4.7-42-g56e9586 into a heap-use-after-free. The src was from kdave's mirror,
devel branch. CFLAGS='-DNDEBUG -O1 -g -fsanitize=address
-fno-omit-frame-pointer -fno-optimize-sibling-calls'


The juicy parts:
==32639==ERROR: AddressSanitizer: heap-use-after-free on address
0x621000019170 at pc 0x0000005c046e bp 0x7fff631e48d0 sp 0x7fff631e48c8
READ of size 4 at 0x621000019170 thread T0
    #0 0x5c046d in free_extent_buffer
/home/lukas/dev/btrfsprogs_fuzz/src/extent_io.c:579:10
    #1 0x59356c in btrfs_release_all_roots
/home/lukas/dev/btrfsprogs_fuzz/src/disk-io.c:1084:3
    #2 0x5949a7 in __open_ctree_fd
/home/lukas/dev/btrfsprogs_fuzz/src/disk-io.c:1325:2
    #3 0x594325 in open_ctree_fs_info
/home/lukas/dev/btrfsprogs_fuzz/src/disk-io.c:1363:9
    #4 0x51e717 in cmd_check
/home/lukas/dev/btrfsprogs_fuzz/src/cmds-check.c:11320:9
    #5 0x4f0f81 in main /home/lukas/dev/btrfsprogs_fuzz/src/btrfs.c:243:8
    #6 0x7f5ce75ee730 in __libc_start_main (/lib64/libc.so.6+0x20730)
    #7 0x4213f8 in _start (/home/lukas/dev/btrfsfuzz/bin/bin/btrfs+0x4213f8)


Note that the bug happens within core itself. The kernel may be vulnerable as
well, I didn't check, though.